Net Effect of Urbanization on Vegetation Dynamics in Arid Regions: Spatiotemporal Patterns and Driving Mechanisms

Rapid urbanization significantly influences vegetation dynamics in ecologically fragile arid regions, but comprehensive quantification of its net effects remains limited. This study aims to analyze the spatiotemporal patterns and underlying driving mechanisms of urbanization’s net impact on vegetation growth, quantified as the Urban Background Difference (UBD = EVI_urban − EVI_rural), across China’s arid regions (Aridity Index < 0.5; precipitation < 500 mm/year) from 2000 to 2020.We integrated Landsat-derived Enhanced Vegetation Index (EVI), Global Artificial Impervious Area (GAIA) data, and multiple auxiliary factors including climate, socioeconomic variables, urban form, and topography. An urban–rural gradient framework was established to assess spatial variation. Driving factors were identified using an XGBoost machine learning model combined with SHapley Additive exPlanations (SHAP) for interpretability.Vegetation exhibited a consistent “core greening, peripheral browning” spatial pattern with significant heterogeneity: UBD was positive in western oasis cities (e.g., Kashi_West: 0.25), attributed to effective water management and economic growth, but negative in eastern grassland areas (e.g., Hulun_Buir: −0.16), constrained by conservation policies. UBD increased significantly between 2000 and 2010 (from 0.05 to 0.12), then diverged post-2010 with sharp declines linked to ecological zoning policies. SHAP analysis identified third-quarter precipitation and annual temperature as major negative drivers, while gross regional product, population density, built-up area proportion, and land-use diversity had positive effects. The barren land ratio accounted for 39.78% of UBD variance.Urbanization’s net impact on vegetation in arid regions is spatially heterogeneous and sensitive to policy interventions. Sustainable urban expansion in drylands requires tailored strategies that balance water resource management, economic development, and optimized urban form.